The present invention relates to a control system for an air conditioner, in particular, to a system for controlling parameters such as room air temperature, air flow velocity, relative humidity, etc.
In a prior art air conditioner, the room air temperature is controlled using a temperature controller set at a predetermined level and detecting the actual room air temperature. In general, the air conditioner is designed so as to hold the room air temperature at a predetermined level when the thermal load is maximum at midsummer. Furthermore, occupants of the room or controlled space must change the set point of the temperature controller when the mean skin temperature, the temperature which occupants feel, varies because of variations of external conditions. The mean skin temperature determines the thermal comfort condition.
It is known that the mean skin temperature is related to the room air temperature, the relative humidity and the air flow velocity as well as to the radiation temperature in a room space. Thus, if the room air temperature is set for a thermal comfort condition at the maximum thermal load, that is, a high radiation temperature, occupants feel colder when the radiation temperature becomes lower in the evening or at night. Accordingly, residents must operate a temperature control dial to change the room air temperature in the evening or at night.
If they do not operate the dial, they feel uncomfortable. The mean skin temperature is also influenced by the air flow velocity and the relative humidity in a room.
The air flow velocity and the relative humidity can also be changed in response to any changes in the radiation temperature. Furthermore, in the prior art air conditioner, unnecessary power is consumed by keeping the room air temperature unduly low even when the radiation temperature becomes low.